In-game Purchase

When playing computer games, it is a common for them to offer you things you
can buy. This is a funding model that may allow them to give the game away for
free, especially when the game play is so compelling that players are desperate
enough to spend money on game benefits.

Shortcuts

Shortcuts are ways to save longer game play. They can be physical shortcuts,
getting you from A to B without having to to via C. They can also save time and
effort in other ways such as working out puzzles and generally gaining
experience.

In many ways most of the other purchases are also shortcuts as they save time
and effort. Other things unavailable through the game may also be bought.

Knowledge

The simplest thing to sell is knowledge. How to get out of the maze. Where
the treasure is buried. What your opponents may do next. Knowledge is power and
can give great advantage.

Resource

Resources of all kinds may be bought, from extra weapons to time available to
play. Sometimes this gives permanent advantage, and sometimes it offers
shorter-term benefit. Sometimes purchase saves time and effort, and sometimes
the only way to get something is to buy it.

Access

Some things may be unavailable in the game or take time to achieve. Payment
can give instant access to areas otherwise inaccessible, to people and groups,
to bonus play and to other desirable things.

Restoration

Games, like life, are full of decisions where the outcome is unclear. And as
with life the player may well regret decisions made. This gives the opportunity
to sell them a replay, going back in time, undoing what has happened and trying
again.

This can be very desirable in games where choices can be fatal to one's
character. Paradoxically, this can be particularly profitable as players take
more risks as they think 'I can always buy reincarnation'.

Ability

Enablement can be sold in various ways. The simplest way is to give the
player extra skills, strength, magical spells and so on, that they can use at
will. This can be permanent enhancement or a temporary boost.

Events

All kinds of events can be bought, from acts of god and deus ex machina, to
parties and storms. Things that happen are different from items. They are verbs
more than nouns. When players think 'I want' they often seek actions rather than
things.

Discussion

The simplest way of selling things is to have a storefront where players can
pick what they want. This can be available at the start, throughout the game or
at specific points. Purchases can be shortcuts or items unavailable elsewhere.

In-game purchase can be particularly effective when the player is stuck, and
is desperate to move on or escape a difficult situation. With care, games can be
designed to make this happen, drawing in the player then precipitating events
that cause desperation.

Is this pay-for-advantage cheating? Probably, though this calls into question
what exactly 'cheating' is. Cheating can be gaining advantage without using
skill or effort, in which case paying is clearly cheating. But when it is
available to all, is that OK? Cheating implies unfairness and inequality. People
with more money can gain advantage others can't afford, which is surely unfair.
But that's life.

If enough dislike the imbalance that in-game purchases creates, then they
will abandon the game and income for the game's managers will fall. This
free-market effect acts as an effectively regulator. Social forces help too, as
those who buy too much may be shunned.